Dual 18v battery adapter for 40v Ryobi tools from JPElectron.com on Tindie
Rechargeable Battery 6.0AH 18V Li-ion For Ryobi Battery ONE+ RB18L40RB18L50RB18L60 18650 Lithium Bateria Charger Combination Set - AliExpress
Battery RAK - 3 hole for RYOBI® 18v ONE+ - JDS Customs
Amazon.com: 3 Port Battery Charger Bundle with Ryobi Charger and Buho Tool Bag, Including 2 Each Ryobi USB Lithium 4-Volt Batteries - Consecutively Charge and Maintain 3 Batteries : Tools & Home Improvement